NAS vs SAN
Learn the difference between NAS and SAN scalabale data storage devices.
The IT industry has a deserved reputation for confusing people with jargon, but never more so than in the world of storage where it has adopted the competing-but-similar terms “NAS” and “SAN” to describe large-scale data storage appliances.
To understand NAS and SAN, you first need to get your head around “DAS”, or direct-attached storage. DAS refers to disks installed inside a server. Every server needs some DAS, in order to store its operating system and other vital data. But DAS can only scale so far to store all the data a business generates, a server would need space to house many, many disk drives. If servers could do so, they would quickly become untenably large and power-hungry.
The industry’s response to this conundrum is dedicated storage appliances that do nothing but house disk drives.
Now that you know about DAS and its limitations, it’s time to think about the things you use your server for. Most of you store all manner of files on your servers. Others will be familiar with servers that run important applications.
Those of you who rely on servers for file storage will quickly understand the main role of NAS – or network attached storage. NAS devices offer a pool of storage that many users or servers can use. NAS devices are pretty simple: connect one to a local area network and it won’t take long before you can let your PCs and servers know that it’s available as a central source of storage. Because NAS can scale to capacities well beyond those of individual servers, many organisations appreciate their ability to let them store an awful lot of data without also acquiring a lot of servers. Modern NAS are also very good at data protection.
SANs are a little more complicated, and to understand why consider the servers you use to run applications. Those machines possess power to burn so they can crunch data in a hurry. DAS makes that easy: the insides of a server offer wonderfully fast data communications. SANs therefore offer specialised connectivity options called iSCSI or Fibre Channel so that even though they store data outside the server, applications can get their digital hands on it in a hurry. You end up with all the benefits of an external, dedicated, storage appliance and keep the speed applications crave at the same time.
Which one is for you? If you’re after scalable file storage, think NAS. If you want a big pool of storage to support applications, you’re probably a prospect for a SAN.
I hope that clears things up, but I also have some bad news: the industry is now rather keen on “unified storage” that blends the best of NAS and SAN in a single device. Don’t let this innovation make you cry out in frustration: there are still plenty of dedicated NAS and SAN devices out there!
This blog was first published at IBM Business Insights Blog and is republished here with kind permission of the author.
Simon Sharwood is an award winning technology writer and editor who happily steers away from gadgets and instead covers data storage, security and technology management for audiences that range from small business to the largest enterprise. The editor of TechTarget Australia New Zealand and Government Technology Review, Simon is also a a non-executive board member of the Storage Networking Industry Association. Find out more about Simon at his company website www.jargonmaster.com
